This invention relates generally to filter systems and more particularly concerns filter systems for removing particles from suspension in a fluid.
Filter systems will herein be explained in relation to those used to clean diesel engine lubricating oil. This application is selected because it is common to filter systems and because it is the application from which this invention was conceived. Those skilled in the art of filter systems will readily recognize, however, that many other applications exist as well.
Diesel engines cannot operate without lubricating oil and quickly fail if the cleanliness of the lubricating oil is not satisfactorily maintained. A typical lubricating oil circuit for a diesel engine is illustrated in FIG. 1. A pump P pulls oil from the sump S, and pushes it through a full-flow device F, which is the primary barrier to solid debris, from which it returns to the lubrication task in the engine E. In some circuits, such as the one shown, the full-flow device F is augmented by the use of a bypass device B, where a fraction of oil in comparison to that moving through the full-flow device F is cleaned of much smaller debris than is trapped in the full-flow device F. The bypass device B, however, is connected directly between the pump P and the sump S and is not in the flow path of the full-flow device F.
Full-flow devices F which use disposable filter screens generate waste, the disposal of which requires time and money and imposes long-term legal responsibility on the engine owner. In some cases, the total cost of disposing of a media-type filter approximates its acquisition cost. The use of cleanable screens rather than disposable screens as a full-flow device F with a self-powered centrifuge as the bypass B device according to FIG. 1 is now common in on-road heavy-duty diesels. This combination provides cleaner lubricating oil than can be achieved with disposable filter screens alone, but little impact has been made in resolving the other problems associated with disposable filters.
Many filter systems have been designed for use in a variety of applications including, but not limited to, cleaning diesel engine lubricating oil, in which a back-flush or reverse flow circuit is used to clean the filter barrier. Flow reversal is achieved by use of valves responsive to variations in the input to output pressure differential of the system or to a timing or other control mechanism which automatically cycles the flow direction. Such circuits involve additional components, maintenance and cost and require interruption and reversal of the normal operating flow patterns.
Still other systems use mechanical devices such as rotating scrubbers to clean the barrier. Such modifications are also more costly and maintenance demanding and are highly susceptible to failure.
It is, therefore, an object of this invention to provide a filter system for removing particles from a fluid which has extended operating time in comparison to known disposable and cleanable filters. Another object of this invention is to provide a filter system for removing particles from a fluid which has greater cleaning capacity in comparison to known disposable and cleanable filters. A further object of this invention is to provide a filter system for removing particles from a fluid which tends to self-clean during its normal operation. Yet another object of this invention is to provide a filter system for removing particles from a fluid which does not require back-flow to clean its particle barrier. It is also an object of this invention to provide a filter system for removing particles from a fluid which applies a centrifuge to the dirty side of the barrier to assist in washing collected particles from the barrier dirty side surface. Still another object of this invention is to provide a filter system for removing particles from a fluid which can use a wedgewire barrier so as to enhance the self-cleaning tendency. An additional object of this invention is to provide a filter system for removing particles from a fluid which can use a semi-conically apertured thin-walled metal barrier so as to enhance the self-cleaning tendency. Another object of this invention is to provide a filter system for removing particles from a fluid which is applicable to original equipment and after-market use. And it is an object of this invention to provide a filter system for removing particles from a fluid which reduces the waste disposal problems of known disposable and cleanable filters.